A file with garbage is created when I run the sample AecSDKDemo

I am using the following command line parameters:

aecsdkdemo -out MicOut.pcm -mod 0 -spkdev 0 -micdev 0

But the file that is produced, MicOut.pcm, seems to contain random
noise. I have verified that my mike is working correctly. The mike
does use the format WAVE_FORMAT_IEEE_FLOAT, which may be the problem.
I am using Visual Studio 2008 and Windows 7 Ultimate.

Any idea what I am doing wrong here?